<script>
const cityOptions = ['上海', '北京', '广州', '深圳']
export default {
  name: 'el_checkbox',
  data() {
    return {
      checked: true,
      checked1: true,
      checked2: true,
      checkList: ['选中且禁用','复选框 A'],
      checkAll: false,
      checkedCities: ['上海', '北京'],
      cities: cityOptions,
      isIndeterminate: true,
      checkedCities2: ['上海', '北京'],
      cities2: cityOptions,
      checkboxGroup1: ['上海'],
      checkboxGroup2: ['上海'],
      checkboxGroup3: ['上海'],
      checkboxGroup4: ['上海'],
      cities3: cityOptions,
      checked3: true,
      checked4: false,
      checked5: false,
      checked6: true,
      checkboxGroup5: [],
      checkboxGroup6: [],
    };
  },
  methods: {
    handleCheckAllChange(val) {
      this.checkedCities = val ? cityOptions : [];
      this.isIndeterminate = false;
    },
    handleCheckedCitiesChange(value) {
      let checkedCount = value.length;
      this.checkAll = checkedCount === this.cities.length;
      this.isIndeterminate = checkedCount > 0 && checkedCount < this.cities.length;
    }
  }
}

</script>

<template>
  <div class="root_el_checkbox">
    <h2>Checkbox 多选框</h2>
    <h5>一组备选项中进行多选</h5>
    <h2>一、基础用法</h2>
    <h5>单独使用可以表示两种状态之间的切换，写在标签中的内容为 checkbox 按钮后的介绍。</h5>
    <p>在el-checkbox元素中定义v-model绑定变量，单一的checkbox中，默认绑定变量的值会是Boolean，选中为true。</p>
    <el-checkbox v-model="checked">选项一</el-checkbox>

    <h2>禁用状态</h2>
    <h5>多选框不可用状态。设置disabled属性即可。</h5>
    <el-checkbox v-model="checked1" disabled>备选项1</el-checkbox>
    <el-checkbox v-model="checked2" disabled>备选项</el-checkbox>


    <h2>二、多选框组</h2>
    <h5>适用于多个勾选框绑定到同一个数组的情景，通过是否勾选来表示这一组选项中选中的项。</h5>
    <p>checkbox-group元素能把多个 checkbox 管理为一组，只需要在 Group 中使用v-model绑定Array类型的变量即可。
      el-checkbox 的 label属性是该 checkbox 对应的值，若该标签中无内容，则该属性也充当 checkbox 按钮后的介绍。
      label与数组中的元素值相对应，如果存在指定的值则为选中状态，否则为不选中。
    </p>
    <el-checkbox-group v-model="checkList">
      <el-checkbox label="复选框 A"></el-checkbox>
      <el-checkbox label="复选框 B"></el-checkbox>
      <el-checkbox label="复选框 C"></el-checkbox>
      <el-checkbox label="禁用" disabled></el-checkbox>
      <el-checkbox label="选中且禁用" disabled></el-checkbox>
    </el-checkbox-group>

    <h2>三、indeterminate 状态</h2>
    <h5>indeterminate 属性用以表示 checkbox 的不确定状态，一般用于实现全选的效果</h5>
    <el-checkbox :indeterminate="isIndeterminate" v-model="checkAll" @change="handleCheckAllChange">全选</el-checkbox>
    <div style="margin: 15px 0;"></div>
    <el-checkbox-group v-model="checkedCities" @change="handleCheckedCitiesChange">
      <el-checkbox v-for="city in cities" :label="city" :key="city">{{city}}</el-checkbox>
    </el-checkbox-group>

    <h2>四、可选项目数量的限制</h2>
    <h5>使用 min 和 max 属性能够限制可以被勾选的项目的数量。</h5>
    <el-checkbox-group
        v-model="checkedCities2"
        :min="1"
        :max="2">
      <el-checkbox v-for="city in cities2" :label="city" :key="city">{{city}}</el-checkbox>
    </el-checkbox-group>

    <h2>五、按钮样式</h2>
    <h5>按钮样式的多选组合。</h5>
    <p>只需要把el-checkbox元素替换为el-checkbox-button元素即可。此外，Element 还提供了size属性。</p>
    <div>
      <el-checkbox-group v-model="checkboxGroup1">
        <el-checkbox-button v-for="city in cities3" :label="city" :key="city">{{city}}</el-checkbox-button>
      </el-checkbox-group>
    </div>
    <div style="margin-top: 20px">
      <el-checkbox-group v-model="checkboxGroup2" size="medium">
        <el-checkbox-button v-for="city in cities3" :label="city" :key="city">{{city}}</el-checkbox-button>
      </el-checkbox-group>
    </div>
    <div style="margin-top: 20px">
      <el-checkbox-group v-model="checkboxGroup3" size="small">
        <el-checkbox-button v-for="city in cities3" :label="city" :disabled="city === '北京'" :key="city">{{city}}</el-checkbox-button>
      </el-checkbox-group>
    </div>
    <div style="margin-top: 20px">
      <el-checkbox-group v-model="checkboxGroup4" size="mini" disabled>
        <el-checkbox-button v-for="city in cities3" :label="city" :key="city">{{city}}</el-checkbox-button>
      </el-checkbox-group>
    </div>

    <h2>六、带有边框</h2>
    <h5>设置border属性可以渲染为带有边框的多选框。</h5>
    <div>
      <el-checkbox v-model="checked3" label="备选项1" border></el-checkbox>
      <el-checkbox v-model="checked4" label="备选项2" border></el-checkbox>
    </div>
    <div style="margin-top: 20px">
      <el-checkbox v-model="checked5" label="备选项1" border size="medium"></el-checkbox>
      <el-checkbox v-model="checked6" label="备选项2" border size="medium"></el-checkbox>
    </div>
    <div style="margin-top: 20px">
      <el-checkbox-group v-model="checkboxGroup5" size="small">
        <el-checkbox label="备选项1" border></el-checkbox>
        <el-checkbox label="备选项2" border disabled></el-checkbox>
      </el-checkbox-group>
    </div>
    <div style="margin-top: 20px">
      <el-checkbox-group v-model="checkboxGroup6" size="mini" disabled>
        <el-checkbox label="备选项1" border></el-checkbox>
        <el-checkbox label="备选项2" border></el-checkbox>
      </el-checkbox-group>
    </div>

  </div>

</template>

<style>
.root_el_checkbox {
  margin-left: 300px;
  margin-right: 300px;
  text-align: left;
}


</style>